She began singing to herself and talking about visions she sees of her father's grave. Ophelia does not know that hamlet killed her father. Ophelia cries out in act 4 sc 5 “Oh heat, dry up my brains! Tears seven times salt Burns out sense and virtue of mine eye!” Later still in act 4, but sc 7 Ophelia drowns. It is explained that she was in a tree and fell. The Queen though sheds some light on it which makes it appear as suicidal. “Her clothes spread wide, And mermaid-like awhile they bore her up, Which time she chanted snatches of lauds…” Showing that Ophelia was singing as she was slowly engulfed by water is a little on the insane side of things. This information of she chanting is vital in the scene with the grave